A manufacturing cell for automotive body assembly has multiple devices that work in close proximity. Stamped sheet metal parts, or the like, are loaded into a fixture consisting of many locating pins and clamps. The clamps close to hold the parts immobile and in proper alignment and then machinery to join the parts moves to engage them. The most common joining technique is resistance spot welding in which a welding gun is moved from welding location to location, manually or robotically. Similar workpiece holding and joining operations are performed in the manufacture of many products.
A new development in such manufacturing operations is the availability of programmable fixtures for parts to be joined. Fixturing elements are carried by programmable robotic devices and can thus be repositioned for production of several different assemblies in the same manufacturing space or cell. In a more conventional cell, the fixtures may either be fixed or may slide or rotate into place, driven by air cylinders.
The design or manufacturing layout of such cells requires elimination of interference between the parts and the various manufacturing devices and the avoidance of any collisions as the devices move. The layout task becomes more difficult as more moving devices operate in the same work volume and as the cell is designed to produce more than one specific assembly, as is the case for programmable fixtures.
In order to best utilize programmable fixtures, it is desirable and necessary to have a computer-aided method for designing such a manufacturing cell so that proper operation of the cell can be verified in simulation before construction of the actual equipment proceeds. In addition, the motions planned in simulation can be stored and used when the applicable part is being produced.